Đây là ví dụ của tôi về truy vấn:
SELECT
nickname,
CASE class_id
WHEN 1 THEN 'Druid'
WHEN 2 THEN 'Necromancer'
WHEN 3 THEN 'Mage'
WHEN 4 THEN 'Priest'
WHEN 5 THEN 'Warrior'
WHEN 6 THEN 'Stalker'
WHEN 7 THEN 'Paladin'
WHEN 8 THEN 'Psionic'
END class_name,
ROUND(AVG(level),2) level,
ROUND(AVG(tabard_id),2) tabard,
CASE rank_id
WHEN 1 THEN 'Leader'
WHEN 2 THEN 'Officer'
WHEN 3 THEN 'Veteran'
WHEN 4 THEN 'HonoryMember'
WHEN 5 THEN 'OrdinaryMember'
WHEN 6 THEN 'Alt'
WHEN 7 THEN 'Apprentice'
WHEN 8 THEN 'Penalty'
END rank_name,
ROUND(AVG(loyality),2) loyality,
ROUND((MAX(authority)-MIN(authority))/AVG(tabard_id)) authority_effective,
MAX(authority)-MIN(authority) authority_delta,
MIN(authority) authority_begin,
MAX(authority) authority_end
FROM users
LEFT JOIN level_history ON level_history.users_id = users.id
LEFT JOIN tabard_history ON tabard_history.users_id = users.id
LEFT JOIN rank_history ON rank_history.users_id = users.id
LEFT JOIN loyality_history ON loyality_history.users_id = users.id
LEFT JOIN authority_history ON authority_history.users_id = users.id
LEFT JOIN guilds_has_users ON guilds_has_users.users_id = users.id
LEFT JOIN report ON report.id = authority_history.report_id
AND report.id = level_history.report_id
AND report.id = loyality_history.report_id
AND report.id = rank_history.report_id
AND report.id = tabard_history.report_id
WHERE report.date BETWEEN '2011-10-24 00:00:00' AND '2011-10-30 23:59:59'
AND guilds_has_users.active = 1
GROUP BY users.id;Giải thích về lựa chọn đó:
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE guilds_has_users ref fk_guilds_has_users_users1,active_IDX active_IDX 1 const 139 Using where; Using temporary; Using filesort
1 SIMPLE users eq_ref PRIMARY PRIMARY 4 z92985_orlandino.guilds_has_users.users_id 1
1 SIMPLE level_history ref fk_level_history_users1,fk_level_history_report1,u... fk_level_history_users1 4 z92985_orlandino.guilds_has_users.users_id 1 Using where
1 SIMPLE report eq_ref PRIMARY,date_IDX,id_date_IDX PRIMARY 4 z92985_orlandino.level_history.report_id 1 Using where
1 SIMPLE tabard_history ref fk_tabard_history_users1,fk_tabard_history_report1... fk_tabard_history_users1 4 z92985_orlandino.level_history.users_id 1 Using where
1 SIMPLE rank_history ref fk_rank_history_users1,fk_rank_history_report1,use... fk_rank_history_users1 4 z92985_orlandino.users.id 1 Using where
1 SIMPLE loyality_history ref fk_loyality_history_users1,fk_loyality_history_rep... fk_loyality_history_users1 4 z92985_orlandino.rank_history.users_id 1 Using where
1 SIMPLE authority_history ref fk_authority_history_users1,fk_authority_history_r... fk_authority_history_users1 4 z92985_orlandino.level_history.users_id 1 Using whereHồ sơ của lựa chọn đó cho tôi biết:
(139 total, Query took 4.4918 sec)
Copying to tmp table 4.488318Và một số thông tin về các biến MySQL:
SHOW VARIABLES LIKE '%buffer%';
Variable_name Value
bulk_insert_buffer_size 8388608
join_buffer_size 131072
key_buffer_size 12884901888
myisam_sort_buffer_size 8388608
net_buffer_length 16384
preload_buffer_size 32768
read_buffer_size 131072
read_rnd_buffer_size 25165824
sort_buffer_size 2097144
sql_buffer_result OFFTại sao sao chép vào bảng tmp rất chậm? Làm thế nào để cải thiện tốc độ truy vấn của tôi?
PS: Tôi không thể cấu hình MySQL vì nhà cung cấp dịch vụ lưu trữ của tôi sẽ không cho phép.